User Equipment, Node, and Communication Method

Abstract

To provide user equipment, a node, and a communication method that reduce the time until radio communication using a SCell (secondary cell) is stopped.SOLUTION: In a mobile communication system, user equipment (UE) 100 that performs radio communication with a node 200 using carrier aggregation includes a receiving unit that receives, from the node, information indicating a radio quality condition that should be satisfied, for the user equipment to perform a deactivation process for a secondary cell set in the user equipment, and a control unit that measures radio quality and evaluates whether the radio quality condition is satisfied. The control unit executes the deactivation process for the secondary cell in response to the radio quality condition being satisfied.SELECTED DRAWING: Figure 10

Description

Technical Field

[0001] The present disclosure relates to a user equipment, a node, and a communication method.

Background Art

[0002] In the Third Generation Partnership Project (3GPP (registered trademark; the same shall apply hereinafter)), which is a standardization project for mobile communication systems, technical specifications for carrier aggregation (CA) are defined. A user equipment (UE) may have CA configured by a node (also simply referred to as a "node") of the network of the mobile communication system.

[0003] In CA, a plurality of component carriers (CCs) corresponding to a plurality of serving cells are aggregated, and the UE can perform reception or transmission simultaneously on a plurality of CCs (a plurality of cells). The plurality of CCs may be continuous or discontinuous in the frequency direction. One serving cell is referred to as a primary cell (PCell), and a set of serving cells is formed by configuring one or more secondary cells (SCells) for the UE together with the PCell.

[0004] When CA is configured, there is one radio resource control (RRC) connection between the UE and the network. Addition and deletion of SCells can be executed by RRC signaling. Activation and deactivation of SCells can be executed by a medium access control (MAC) control element (CE).

[0005] Deactivation of an SCell in CA is generally performed in the following procedure. First, the UE transmits a measurement report message including measurement results of the radio quality of each cell to the node. Second, the node deactivates the SCell of the UE using a MAC CE based on the measurement report message. By deactivating the SCell, the SCell transitions from an active state to an inactive state, and wireless communication using the SCell is stopped.

[0006] Such control of deactivation has a problem that it is difficult to shorten the time from when the radio quality corresponding to the SCell deteriorates in the UE until the radio communication using the SCell is stopped, which may result in waste of power consumption and radio resources.

Prior Art Documents

Non-Patent Documents

[0007]

Non-Patent Document 1

Summary of the Invention

[0008] A user equipment according to a first aspect is a user equipment that performs radio communication with a node using carrier aggregation in a mobile communication system, and for a secondary cell set in the user equipment, a receiving unit that receives information indicating radio quality conditions to be satisfied for the user equipment to perform a deactivation process from the node, and a control unit that measures radio quality and evaluates whether the radio quality conditions are satisfied. The control unit executes the deactivation process for the secondary cell in response to the radio quality conditions being satisfied.

[0009] A node according to a second aspect is a node that performs radio communication with a user equipment using carrier aggregation in a mobile communication system, and includes a control unit that sets a secondary cell in the user equipment, and a transmission unit that transmits information indicating radio quality conditions to be satisfied for the user equipment to perform a deactivation process for the secondary cell to the user equipment.

[0010] The communication method according to the third aspect is a communication method used in a user equipment that performs wireless communication with a node using carrier aggregation in a mobile communication system, and includes a step of receiving, from the node, information indicating a radio quality condition to be satisfied for the user equipment to execute a deactivation process for a secondary cell set in the user equipment, a step of measuring radio quality and evaluating whether the radio quality condition is satisfied, and a step of executing the deactivation process for the secondary cell in response to the radio quality condition being satisfied.

[0011] The communication method according to the fourth aspect is a communication method used in a node that performs wireless communication with a user equipment using carrier aggregation in a mobile communication system, and includes a step of setting a secondary cell for the user equipment, and a step of transmitting, to the user equipment, information indicating a radio quality condition to be satisfied for the user equipment to execute a deactivation process for the secondary cell.

Brief Description of the Drawings

[0012]

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Embodiments for Carrying Out the Invention

[0013] Hereinafter, with reference to the drawings, a mobile communication system according to an embodiment will be described. In the description of the drawings, the same or similar parts are denoted by the same or similar reference numerals.

[0014] (1) First Embodiment The first embodiment will be described with reference to FIGS. 1 to 10.

[0015] (1.1) System Configuration Example FIG. 1 is a diagram showing a configuration example of a mobile communication system according to an embodiment. The mobile communication system according to the embodiment is a system compliant with the 3GPP standard. For example, the mobile communication system according to the embodiment may be a fifth-generation (5G) system or a sixth-generation (6G) system.

[0016] The mobile communication system includes a network (NW) 1 and a user equipment (UE) 100. The UE 100 is a movable communication device that performs wireless communication with the NW 1. The UE 100 may be any device used by a user, for example, a mobile phone terminal (including a smartphone), a tablet terminal, a notebook PC (Personal Computer), a communication module (including a communication card or a chipset), a sensor or a device provided for the sensor, a vehicle or a device provided for the vehicle (Vehicle UE), an aircraft or a device provided for the aircraft (Aerial UE).

[0017] The NW 1 includes a radio access network (RAN) 10 and a core network (CN) 20. When the mobile communication system is a fifth-generation system (5GS: 5th Generation System), the RAN 10 is referred to as an NG-RAN (Next Generation Radio Access Network), and the CN 20 is referred to as a 5GC (5G Core Network).

[0018] The RAN 10 includes a plurality of nodes 200 (in the illustrated example, nodes 200a to 200c). The nodes 200 are interconnected via an inter-node interface. The nodes 200 are also referred to as base stations. The nodes 200 are composed of a CU (Central Unit) and a DU (Distributed Unit) (i.e., functionally split), and the two units may be connected by a front-haul interface. When the mobile communication system is 5GS, the nodes 200 are referred to as gNBs, the inter-node interface is referred to as an Xn interface, and the front-haul interface is referred to as an F1 interface.

[0019] Each node 200 manages one or more cells. The node 200 performs wireless communication with the UE 100 that has established a connection with its own cell. Each node 200 has a radio resource management (RRM) function, a routing function for user data (also simply referred to as "data"), a measurement control function for mobility control and scheduling, etc. Note that "cell" is used as a term indicating the smallest unit of a wireless communication area. "Cell" is also used as a term indicating a function or resource for performing wireless communication with the UE 100. One cell belongs to one carrier frequency (also simply referred to as "frequency").

[0020] The CN 20 includes a CN device 300. The CN device 300 may include a control plane (C-plane) device corresponding to the control plane and a user plane (U-plane) device corresponding to the user plane. The C-plane device performs various mobility controls and paging for the UE 100, etc. The C-plane device communicates with the UE 100 using NAS (Non-Access Stratum) signaling. The U-plane device performs data transfer control. When the mobile communication system is 5GS, the C-plane device is referred to as an AMF (Access and Mobility Management Function), the U-plane device is referred to as a UPF (User Plane Function), and the interface between the node 200 and the CN device 300 is referred to as an NG interface.

[0021] FIG. 2 is a diagram showing a configuration example of a protocol stack of a wireless interface of the U-plane that handles data.

[0022] The wireless interface protocol of the U-plane has, for example, a physical (PHY) layer, a MAC (Medium Access Control) layer, an RLC (Radio Link Control) layer, a PDCP (Packet Data Convergence Protocol) layer, and an SDAP (Service Data Adaptation Protocol) layer.

[0023] The PHY layer performs encoding / decoding, modulation / demodulation, antenna mapping / demapping, and resource mapping / demapping. Between the PHY layer of UE100 and the PHY layer of Node 200, data and control information are transmitted via physical channels. Note that the PHY layer of UE100 receives downlink control information (DCI) transmitted on the physical downlink control channel (PDCCH) from Node 200. Specifically, UE100 performs blind decoding of the PDCCH using a radio network temporary identifier (RNTI) and obtains the DCI that has been successfully decoded as DCI addressed to itself. The DCI transmitted from Node 200 has CRC parity bits scrambled by the RNTI added thereto.

[0024] The MAC layer performs priority control of data and retransmission processing by hybrid automatic repeat request (HARQ), etc. Between the MAC layer of UE100 and the MAC layer of Node 200, data and control information are transmitted via transport channels. The MAC layer of Node 200 includes a scheduler. The scheduler determines the uplink and downlink transport formats (transport block size, modulation and coding scheme (MCS)) and the resources allocated to UE100.

[0025] The RLC layer uses the functions of the MAC layer and the PHY layer to transmit data to the RLC layer on the receiving side. Between the RLC layer of UE100 and the RLC layer of Node 200, data and control information are transmitted via logical channels.

[0026] The PDCP layer performs header compression / decompression, encryption / decryption, etc.

[0027] The SDAP layer performs mapping between an IP flow, which is a unit for QoS control by CN20, and a radio bearer, which is a unit for QoS control by the access stratum (AS). Note that when the RAN is connected to the EPC, the SDAP may not be necessary.

[0028] FIG. 3 is a diagram showing a configuration example of a protocol stack of a radio interface of a C plane that handles signaling (control signals).

[0029] The protocol stack of the radio interface of the C plane has an RRC (Radio Resource Control) layer and an NAS (Non-Access Stratum) layer, for example, instead of the SDAP layer shown in FIG. 2.

[0030] Between the RRC layer of the UE 100 and the RRC layer of the node 200, RRC signaling for various settings is transmitted. The RRC layer controls logical channels, transport channels, and physical channels in response to the establishment, re-establishment, and release of radio bearers. When there is a connection (RRC connection) between the RRC of the UE 100 and the RRC of the node 200, the UE 100 is in the RRC connected state. When there is no connection (RRC connection) between the RRC of the UE 100 and the RRC of the node 200, the UE 100 is in the RRC idle state. When the connection between the RRC of the UE 100 and the RRC of the node 200 is suspended, the UE 100 is in the RRC inactive state.

[0031] The NAS layer (also simply referred to as "NAS") located above the RRC layer performs session management, mobility management, etc. NAS signaling is transmitted between the NAS layer of the UE 100 and the NAS layer of the CN device 300. Note that the UE 100 has an application layer, etc. in addition to the protocol of the radio interface. Also, a layer lower than the NAS layer is referred to as an AS layer (also simply referred to as "AS").

[0032] (1.2) CA using a terahertz wave cell FIG. 4 is a diagram for explaining a terahertz (THz) wave cell according to an embodiment.

[0033] The mobile communication system according to the embodiment may be a 6G system. In 6G, it is assumed to utilize terahertz (THz) waves. A cell operated with THz waves is referred to as a THz wave cell. THz waves have stronger directivity, higher free space loss, and are more susceptible to the influence of the atmosphere and rainfall compared to millimeter waves (mmW). Therefore, a THz wave cell can be an ultra-small cell.

[0034] In the illustrated example, the diameter of the coverage area of the THz wave cell is about 10 [m], the diameter of the coverage area of the mmW cell operated with mmW is about 100 [m], and the diameter of the coverage area of the macro cell is about 1000 [m]. Under such assumptions, for example, the UE100 moving at 60 [km / s] passes through the coverage area of each THz wave cell in about 599 [ms].

[0035] One method for stably controlling small cells in a mobile communication system is carrier aggregation (CA). In the embodiment, it is assumed that the THz wave cell is used as a secondary cell (SCell) of CA. It is assumed that the primary cell (PCell) of CA is a macro cell, but the PCell may be an mmW cell.

[0036] FIG. 5 is a diagram for explaining carrier aggregation (CA) according to the embodiment.

[0037] In the RRC connected state, the UE 100 can have CA configured by the node 200. In CA, multiple component carriers (CCs) corresponding to multiple serving cells are aggregated, and the UE can receive or transmit simultaneously on multiple CCs (multiple cells). The multiple CCs may be contiguous in the frequency domain or non - contiguous. One serving cell is referred to as the primary cell (PCell), and by configuring one or more secondary cells (SCells) for the UE together with the PCell, a set of serving cells is formed. When CA is configured, there is one RRC connection for the UE 100 with the network 1. The addition and deletion of SCells can be performed by RRC signaling. The activation and de - activation of SCells can be performed by media access control (MAC) control elements (CEs).

[0038] The mobile communication system supports the activation and de - activation of cells to reduce the power consumption of the UE 100 when CA is configured. When an SCell is in the de - active state, the UE 100 does not need to receive the PDCCH or the physical downlink shared channel (PDSCH) on the SCell, and cannot perform uplink transmission on the SCell. The UE 100 also does not need to perform channel quality indicator (CQI) measurements for the de - active SCell. On the other hand, when an SCell is in the active state, the UE 100 receives the PDSCH and the PDCCH on the SCell. The UE 100 can perform CQI measurements for the active SCell.

[0039] Note that when the node 200 re - configures the set of serving cells, it first activates or de - activates the SCell added to the set, and the SCells remaining in the set (not changed or re - configured) do not change their activation state (activated or de - activated).

[0040] Figure 6 is a diagram showing a general procedure for the addition and activation of an SCell.

[0041] In step S11, the UE 100 transmits a Measurement Report message including measurement results of the radio quality of each cell to the node 200, for example, on the PCell. The radio quality may be any indicator related to the radio quality. For example, it is at least one of RSRP (Reference Signal Received Power), RSRQ (Reference Signal Received Quality), and SINR (Signal to Interference & Noise Ratio). The Measurement Report message is an RRC message transmitted and received at the RRC layer. The transmission of the Measurement Report message may be performed periodically or triggered by an event. The node 200 receives the Measurement Report message.

[0042] In step S12, based on the Measurement Report message, the node 200 determines to configure (add) an SCell for the UE 100 and transmits an RRC Reconfiguration message for adding the SCell to the UE 100, for example, on the PCell. The RRC Reconfiguration message is transmitted and received at the RRC layer. The UE 100 receives the RRC Reconfiguration message.

[0043] In step S13, the UE 100 transmits an RRC Reconfiguration Complete message indicating that the addition of the SCell based on the RRC Reconfiguration message is completed to the node 200, for example, on the PCell. The RRC Reconfiguration Complete message is transmitted and received at the RRC layer. The node 200 receives the RRC Reconfiguration Complete message. At this stage, the added SCell is in an inactive state.

[0044] In step S14, node 200 transmits, for example, on the PCell, to UE100 a MAC CE for activating the SCell added to UE100. The MAC CE is transmitted and received at the MAC layer. When UE100 receives the MAC CE, it starts activating the SCell. After starting to activate the SCell, UE100 receives the reference signal of the SCell, performs channel state information (CSI) measurement, automatic gain control (AGC), and beam management, and prepares for communication.

[0045] In step S15, UE100 transmits, for example, on the PUCCH of the PCell, to node 200 a HARQ ACK indicating successful reception of the MAC CE. Node 200 receives the HARQ ACK.

[0046] In step S16, when the SCell becomes active in UE100, UE100 and node 200 start wireless communication using the SCell.

[0047] According to such a procedure, it takes, for example, about 35 [ms] from when the radio quality of the SCell becomes communicable until UE100 can use the SCell. When the SCell is a THz wave cell, the coverage area of the SCell becomes even narrower due to the influence of shielding etc., so the time available to use the SCell is short. Therefore, in the procedure of FIG. 6, since it takes a long time until the activation of the SCell is completed, there is a problem that the time actually available to transmit and receive data on the SCell becomes short.

[0048] Here, as a technology capable of accelerating the activation of the SCell, the following extended functions have been introduced up to Release 17 of the 3GPP standard.

[0049] As a first extension function, there is direct SCell activation. In direct SCell activation, when the node 200 adds an SCell to the UE 100 using an RRC message, it can specify the active state as the initial state of the SCell. This eliminates the need to transmit and receive MAC CE for SCell activation in FIG. 6, and can speed up the activation of the SCell.

[0050] As a second extension function, there is a technique called a dormant BWP. The node 200 can set a bandwidth part (BWP) in the dormant state for the SCell. When the active BWP of the activated SCell is the BWP in the dormant state, the UE 100 stops monitoring the PDCCH and transmitting the sounding reference signal (SRS) / PUSCH / PUCCH on the SCell, but continues to perform CSI measurement, AGC, and beam management. PDCCH / downlink control information (DCI) is used to control the entry and exit of the SCell to and from the dormant BWP. Note that the BWP in the dormant state is one of the dedicated BWPs of the UE 100 set by the network 1 via dedicated RRC signaling. An example of using the dormant BWP will be described in the second embodiment.

[0051] As a third extension function, there is a method of setting an aperiodic CSI-RS for tracking (synchronization) for fast SCell activation in the SCell. Such an aperiodic CSI-RS can assist AGC and time / frequency synchronization. The MAC CE is used to trigger (start) the activation of the SCell and trigger the aperiodic CSI-RS for the deactivated SCell.

[0052] FIG. 7 is a diagram showing a general procedure for deactivating an SCell.

[0053] In step S21, in the UE 100, the SCell is in the active state, and the UE 100 and the node 200 are performing wireless communication using the SCell.

[0054] Here, it is assumed that in UE100, the radio quality of the SCell deteriorates, and it becomes difficult to continue wireless communication using the SCell.

[0055] In step S22, UE100 transmits a Measurement Report message including the measurement results of the radio quality of each cell to node 200, for example, on the PCell. Node 200 receives the Measurement Report message.

[0056] In step S23, based on the Measurement Report message, node 200 recognizes the deterioration of the radio quality of the SCell in UE100, and transmits a MAC CE (SCell deactivation MAC CE) for deactivating the SCell of UE100 to UE100, for example, on the PCell. UE100 receives the MAC CE.

[0057] In step S24, UE100 transmits a HARQ ACK indicating successful reception of the MAC CE to node 200, for example, on the PUCCH of the PCell. Node 200 receives the HARQ ACK.

[0058] In step S25, in response to the reception of the MAC CE in step S23, UE100 deactivates the SCell. For example, UE100 stops monitoring the PDCCH and measuring the CQI for the SCell. On the other hand, in response to the reception of the HARQ ACK in step S24, node 200 stops the DL transmission process (PDCCH transmission, PDSCH transmission) on the SCell of UE100. As a result, the wireless communication using the SCell is stopped.

[0059] In the operation shown in FIG. 7, when the radio quality of the SCell in the UE 100 deteriorates, communication on the SCell becomes unavailable. However, the node 200 cannot grasp the deterioration of the radio quality of the SCell until it receives the Measurement Report message in step S22, and may continue the DL transmission process even after the radio quality of the SCell deteriorates. Also, the UE 100 may continue PDCCH monitoring (and CQI measurement) on the SCell until it receives the MAC CE in step S23. In such an operation, there is a problem of waste of resources and power consumption.

[0060] For example, the delay from when the radio quality of the SCell in the UE 100 deteriorates until the Measurement Report message is transmitted is approximately 10 ms, and the delay from when the node 200 receives the Measurement Report message until the SCell deactivation MAC CE is transmitted to the UE 100 may be approximately 10 ms. In this case, waste of resources and power consumption may occur in about 20 ms. Therefore, it is desirable to be able to quickly deactivate the SCell when the radio quality of the SCell no longer satisfies a predetermined quality.

[0061] (1.3) Configuration example of user equipment FIG. 8 is a diagram showing a configuration example of the UE 100 (user equipment) according to the embodiment.

[0062] The UE 100 includes a receiving unit 110, a transmitting unit 120, and a control unit 130. The receiving unit 110 and the transmitting unit 120 constitute a wireless communication unit 140 that performs wireless communication with the node 200.

[0063] The receiving unit 110 performs various receptions under the control of the control unit 130. The receiving unit 110 includes an antenna and a receiver. The receiver converts the radio signal received by the antenna into a baseband signal (received signal) and outputs it to the control unit 130. The transmitting unit 120 performs various transmissions under the control of the control unit 130. The transmitting unit 120 includes an antenna and a transmitter. The transmitter converts the baseband signal (transmission signal) output by the control unit 130 into a radio signal and transmits it from the antenna.

[0064] The control unit 130 performs various controls and processes in the UE 100. The operations of the UE 100 described above and below may be operations under the control of the control unit 230. The control unit 130 includes at least one processor and at least one memory. The memory stores a program executed by the processor and information used for the processing by the processor. The processor may include a baseband processor and a CPU (Central Processing Unit). The baseband processor performs modulation / demodulation and encoding / decoding of the baseband signal, etc. The CPU executes the program stored in the memory and performs various processes.

[0065] The UE 100 configured as described above performs wireless communication with the node 200 using CA. The receiving unit 110 receives, from the node 200, information indicating the radio quality conditions to be satisfied for the UE 100 to perform deactivation processing on the SCell set in the UE 100. The control unit 130 measures the radio quality for the SCell and evaluates whether or not the radio quality conditions are satisfied. The control unit 130 executes deactivation processing for the SCell in response to the satisfaction of the radio quality conditions.

[0066] As a result, when the radio quality of the SCell meets the radio quality condition (for example, the radio quality deteriorates from a predetermined quality), the UE 100 can autonomously perform the deactivation process for the SCell. On the other hand, in the conventional technology, the node 200 needs to recognize that the radio quality of the SCell meets the radio quality condition based on the Measurement Report message and instruct the UE 100 to deactivate the SCell.

[0067] In the embodiment, since the radio quality condition is set for the UE 100 and the UE 100 can determine whether the radio quality condition is met, the UE 100 can autonomously perform the deactivation process for the SCell without transmitting a Measurement Report message to the node 200. Therefore, it is possible to speed up the deactivation of the SCell.

[0068] In the first embodiment, the deactivation process includes a process of transitioning an active SCell to an inactive state. The activation process may include a process of transitioning a BWP in a non-dormant state in the SCell to a dormant state. An example of using a dormant BWP will be described in the second embodiment.

[0069] In the embodiment, the transmission unit 120 transmits a notification regarding the deactivation process to the node 200 in response to the radio quality condition being satisfied. Thereby, the node 200 can grasp that the UE 100 performs the deactivation process based on the notification. Therefore, the wireless communication using the SCell can be smoothly stopped. The notification may be a newly introduced MAC CE. Since the MAC CE is transmitted and received at the MAC layer, a faster transmission process is possible compared to the Measurement Report message.

[0070] In an embodiment, the transmission unit 120 transmits a notification regarding the deactivation process to the node 200 on the PCell. Thereby, even when the radio quality of the SCell deteriorates, the notification can be transmitted to the node 200. Therefore, the wireless communication using the SCell can be smoothly and promptly stopped.

[0071] In an embodiment, when the radio quality condition is satisfied or when a positive acknowledgment (HARQ ACK) for a notification regarding the deactivation process is received from the node 200, the control unit 130 stops the PDCCH monitoring (and CQI measurement) for the SCell. Thereby, it is possible to suppress the waste of resources and power consumption as described above.

[0072] (1.4) Configuration example of the node FIG. 9 is a diagram showing a configuration example of the node 200 (base station) according to the embodiment.

[0073] The node 200 includes a transmission unit 210, a reception unit 220, a control unit 230, and an NW communication unit 240. The transmission unit 210 and the reception unit 220 constitute a wireless communication unit 250 that performs wireless communication with the UE 100.

[0074] The transmission unit 210 performs various transmissions under the control of the control unit 230. The transmission unit 210 includes an antenna and a transmitter. The transmitter converts the baseband signal (transmission signal) output by the control unit 230 into a radio signal and transmits it from the antenna. The reception unit 220 performs various receptions under the control of the control unit 230. The reception unit 220 includes an antenna and a receiver. The receiver converts the radio signal received by the antenna into a baseband signal (reception signal) and outputs it to the control unit 230.

[0075] The control unit 230 performs various controls and processes in the node 200. The operations of the node 200 described above and below may be operations under the control of the control unit 230. The control unit 230 includes at least one processor and at least one memory. The memory stores a program executed by the processor and information used for the processing by the processor. The processor may include a baseband processor and a CPU. The baseband processor performs modulation / demodulation and encoding / decoding of baseband signals, etc. The CPU executes a program stored in the memory to perform various processes.

[0076] The NW communication unit 240 is connected to an adjacent node via a node interface. The NW communication unit 240 is connected to the CN device 300 via an interface between the node and the CN.

[0077] The node 200 configured as described above performs wireless communication with the UE 100 using CA. The control unit 230 sets an SCell for the UE 100. The transmission unit 210 transmits to the UE 100 information indicating radio quality conditions to be satisfied for the UE 100 to execute deactivation processing for the SCell. Thereby, when the radio quality of the SCell satisfies the radio quality conditions, the UE 100 can autonomously perform deactivation processing for the SCell.

[0078] In the embodiment, the reception unit 220 receives a notification regarding deactivation processing from the UE 100 in response to the radio quality conditions being satisfied in the UE 100. For example, the reception unit 220 receives the notification from the UE 100 on the PCell.

[0079] In the embodiment, when the control unit 230 receives a notification regarding the deactivation process, or when it transmits a positive response (HARQ ACK) to the UE 100 for the notification, the DL transmission process (PDCCH transmission, PDSCH transmission) on the SCell is stopped. As a result, compared with the general procedure shown in FIG. 7, the DL transmission process can be stopped earlier, so that the waste of resources and power consumption as described above can be suppressed.

[0080] (1.5) System operation example FIG. 10 is a diagram showing a system operation example according to the first embodiment. In FIG. 10, steps that are not essential are indicated by dashed lines. Also, duplicate descriptions of operations similar to those in FIGS. 6 and 7 are omitted.

[0081] In step S101, the receiving unit 110 of the UE 100 receives a reference signal from each cell, the control unit 130 of the UE 100 measures the radio quality based on the reference signal, and the transmitting unit 120 of the UE 100 transmits a Measurement Report message including the measurement result to the node 200, for example, on the PCell. Here, the Measurement Report message is assumed to include the measurement result of the THz wave cell. The receiving unit 220 of the node 200 receives the Measurement Report message.

[0082] In step S102, the control unit 230 of the node 200 generates an RRC Reconfiguration message, and the transmitting unit 210 of the node 200 transmits the RRC Reconfiguration message to the UE 100, for example, on the PCell. The receiving unit 110 of the UE 100 receives the RRC Reconfiguration message.

[0083] The RRC Reconfiguration message includes, for example, configuration information for adding an SCell, configuration information for setting the activation of the SCell (i.e., information specifying the active state as the initial state of the SCell), and configuration information for conditional SCell deactivation. In the illustrated example, the configuration information for adding an SCell, the configuration information for setting the activation of the SCell, and the configuration information for conditional SCell deactivation are transmitted in one RRC Reconfiguration message, but these pieces of information may be transmitted in separate RRC Reconfiguration messages.

[0084] The configuration information for adding an SCell may be the sCellToAddModList, which is a list of SCell(s) to be added or modified. The sCellToAddModList is a list having SCell configurations (SCellConfig) as entries. Each SCell configuration (SCellConfig) includes the index of the corresponding SCell (sCellIndex) and the configuration of the corresponding SCell (sCellConfigCommon and sCellConfigDedicated).

[0085] The configuration information for conditional SCell deactivation may be included in the SCell configuration (SCellConfig). The configuration information for conditional SCell deactivation may include information for setting the frequency and / or cell ID of the target SCell.

[0086] The configuration information for conditional SCell deactivation includes information indicating the radio quality conditions to be satisfied for the UE100 to deactivate the corresponding SCell.

[0087] Here, the information indicating the radio quality condition may include at least one radio quality threshold among, for example, an RSRP threshold, an RSRQ threshold, and an SINR threshold. Meeting the radio quality condition for the SCell may mean that at least one of the following occurs: the RSRP of the SCell is below the RSRP threshold, the RSRQ of the SCell is below the RSRQ threshold, and the SINR of the SCell is below the SINR threshold.

[0088] The information indicating the radio quality condition may include a threshold for the duration of a state in which a radio problem is detected in a lower layer (e.g., the PHY layer) in the UE 100. In this case, meeting the radio quality condition for the SCell may mean that the duration of the state in which a radio problem is detected for the SCell has reached the threshold.

[0089] The information indicating the radio quality condition may include a threshold for the number of retransmissions that continue in the UE 100 (i.e., the number of consecutive UL data transmission failures). In this case, meeting the radio quality condition for the SCell may mean that the number of retransmissions that continue for the SCell (i.e., the number of consecutive UL data transmission failures for the SCell) has reached the threshold.

[0090] The information indicating the radio quality condition may include a threshold for the time during which UL data transmission cannot be performed based on detecting an interfering wave in the UE 100. For example, when the SCell is operating in an unlicensed band, the UE 100 performs carrier sensing for the SCell and performs UL data transmission only when there is an available channel, and does not perform UL data transmission when there is no available channel. In this case, meeting the radio quality condition for the SCell may mean that the time during which UL data transmission using carrier sensing cannot be performed has reached the threshold.

[0091] In step S103, the control unit 130 of the UE 100 generates an RRC Reconfiguration Complete message, and the transmission unit 210 of the UE 100 transmits the RRC Reconfiguration Complete message to the node 200, for example, on the PCell. The reception unit 220 of the node 200 receives the RRC Reconfiguration Complete message.

[0092] The initial state of the SCell added to the UE 100 may be the active state (step S104). Alternatively, after the SCell is added to the UE 100, the SCell may be activated by a MAC CE (step S104). Note that the control unit 130 of the UE 100 starts radio quality measurement (for example, RSRP measurement, RSRQ measurement, and / or SINR measurement) for the SCell based on the setting information for conditional SCell deactivation.

[0093] In step S105, the reception unit 110 of the UE 100 receives the reference signal of the SCell, and the control unit 130 of the UE 100 measures the radio quality based on the reference signal. The reference signal of the SCell may be the demodulation reference signal (DMRS) included in the SSB (SS / PBCH Block) transmitted by the SCell, or may be a TRS (Tracking Reference Signal) which is a type of CSI-RS. The measurement of the radio quality may include at least one of the measurement of the duration of the state in which a radio problem is detected, the measurement of the number of times of continuous retransmission (that is, the number of times of continuous failure of UL data transmission), and the measurement of the time when UL data transmission cannot be executed.

[0094] In step S106, the control unit 130 of the UE 100 determines whether the radio quality condition set in step S102 is satisfied. For example, the control unit 130 of the UE 100 compares the measurement result (e.g., RSRP, RSRQ, and / or SINR) in step S105 with the radio quality threshold set in step S102. If the measurement result is lower than the radio quality threshold, it is determined that the radio quality condition is satisfied. If it is determined that the radio quality condition is not satisfied (step S106: NO), the process returns to step S105.

[0095] On the other hand, if it is determined that the radio quality condition is satisfied (step S106: YES), in step S107, the control unit 130 of the UE 100 deactivates the SCell. For example, the control unit 130 of the UE 100 stops processing such as PDCCH monitoring for the SCell. Note that the SCell deactivation may be performed when receiving an affirmative response (HARQ ACK) in step S109.

[0096] In step S108, the control unit 130 of the UE 100 triggers the transmission of an SCell deactivation notification, and the transmission unit 120 of the UE 100 transmits the SCell deactivation notification to the node 200 on the PCell. The receiving unit 220 of the node 200 receives the SCell deactivation notification.

[0097] The SCell deactivation notification may be a newly introduced MAC CE. For example, the SCell deactivation notification includes the index value (which may also be a cell ID) of the deactivated SCell. However, the SCell deactivation notification may be a notification included in UCI transmitted on the PUCCH, or may be a PDCP Control PDU, or may be a notification included in an RRC message.

[0098] The SCell deactivation notification may include the index of the activated SCell. The index may refer to each entry in the list of SCell configurations set in the RRC Reconfiguration. Instead of the index, the cell ID of the activated SCell may be notified. Or, in the bitmap-like notification, each bit position may be associated with each SCell, and each bit (0 / 1) may indicate whether it has been activated or not.

[0099] The SCell deactivation notification may include information on the timing when the SCell deactivation (i.e., step S107) is performed. The timing information may be the radio frame number when the SCell deactivation is executed, or may be expressed by any one or combination of the system frame number, subframe number, slot number, and symbol number. The timing information may be the time information when the SCell deactivation is executed. The timing information may be the elapsed time from when the SCell deactivation is executed until the SCell deactivation notification is transmitted, and may be expressed in seconds (e.g., milliseconds), or may be expressed in the number of radio frames (e.g., the number of slots). With such timing information, the node 200 can know when the DL reception in the SCell stops, and can efficiently identify the data packets to be retransmitted when retransmitting the data transmitted during the period in the PCell.

[0100] Prior to transmitting the SCell deactivation notification, the following processes may be performed at the PHY layer and the MAC layer. Specifically, the UE 100 transmits an SR (Scheduling Request) to the node 200, the node 200 transmits a UL grant for BSR (Buffer Status Report) to the UE 100, the UE 100 transmits a BSR to the node 200, and the node 200 transmits a UL grant for PUSCH transmission to the UE 100. Then, the UE 100 transmits an SCell deactivation notification based on the UL grant for PUSCH transmission.

[0101] Although an example in which the UE 100 transmits an SCell deactivation notification to the node 200 on the PCell has been described, when deactivating the SCell upon receiving a positive acknowledgment (HARQ ACK), the SCell deactivation notification may be transmitted to the node 200 on the SCell.

[0102] In step S109, the transmission unit 210 of the node 200 transmits a HARQ ACK indicating successful reception of the SCell deactivation notification to the UE 100 on the PDCCH of the PCell. The reception unit 110 of the UE 100 receives the HARQ ACK. Note that when the SCell deactivation notification is UCI, step S109 may not be performed.

[0103] In response to receiving the SCell deactivation notification in step S108, the node 200 recognizes that the SCell of the UE 100 has become unavailable. In step S110, the node 200 stops DL transmission to the UE 100 via the SCell.

[0104] (2) Second Embodiment Referring to FIGS. 11 and 12, the second embodiment will be mainly described in terms of differences from the first embodiment.

[0105] (2.1) BWP FIG. 11 is a diagram for explaining BWP.

[0106] With bandwidth adaptation (BA), it is not necessary for the transmission and reception bandwidth of UE100 to be as large as the cell bandwidth and can be adjusted. A part of the cell bandwidth (which may also be referred to as "system bandwidth" or "carrier bandwidth") is called a BWP. In BA, Node 200 sets one or more BWPs for UE100 within the cell and notifies UE100 which of the set BWPs is currently active. There are an initial BWP used for initial access and a dedicated BWP individually set for UE100 in the BWP. The bandwidth and subcarrier spacing of each BWP can be variably set.

[0107] In the illustrated example, three different BWPs are set for UE100, showing an example of switching the active BWP among these BWPs. BWP1 has a width of 40 [MHz] and a subcarrier spacing of 15 [kHz], BWP2 has a width of 10 MHz and a subcarrier spacing of 15 kHz, and BWP3 has a width of 20 MHz and a subcarrier spacing of 60 kHz.

[0108] In each of UL and DL, there is only one active BWP, and the rest are in an inactive state. In an inactive state BWP, UE100 does not monitor PDCCH and does not perform transmission of PUCCH, PRACH, and UL-SCH (PUSCH).

[0109] In the case of CA, Node 200 can set a dormant state BWP (dormant BWP) for the SCell. When the active BWP of the activated SCell is the dormant state BWP, UE100 stops PDCCH monitoring and SRS / PUSCH / PUCCH transmission on the said SCell, but continues to perform CSI measurement, AGC, and beam management. PDCCH / DCI is used to control the entering and leaving of the dormant BWP for the SCell. Note that the dormant state BWP is one of the dedicated BWPs of UE100 set by Node 200 via dedicated RRC signaling.

[0110] (2.2) System operation example Similar to the first embodiment, the UE 100 according to the second embodiment performs wireless communication with the node 200 using CA. The receiving unit 110 receives, from the node 200, information indicating the radio quality conditions that should be satisfied for the UE 100 to perform deactivation processing on the SCell set in the UE 100. The control unit 130 measures the radio quality for the SCell and evaluates whether the radio quality conditions are satisfied. The control unit 130 executes deactivation processing for the SCell in response to the satisfaction of the radio quality conditions. In the second embodiment, the deactivation processing includes a dormancy transition process that transitions the BWP in the non-dormant state to the dormant state in the SCell.

[0111] According to the second embodiment, the control unit 130 of the UE 100 transitions the BWP in the non-dormant state to the dormant state for the active SCell in response to the satisfaction of the radio quality conditions set by the node 200. Thereby, it is possible to autonomously transition the BWP in the non-dormant state to the dormant state without transmitting a Measurement Report message to the node 200 and receiving a DCI indicating the transition of the dormant BWP.

[0112] FIG. 12 is a diagram showing an example of system operation according to the second embodiment. In FIG. 12, steps that are not essential are indicated by dashed lines. Also, duplicate explanations for operations similar to those of the first embodiment described above are omitted.

[0113] In step S201, the receiving unit 110 of UE100 receives reference signals from each cell, the control unit 130 of UE100 measures the radio quality based on the reference signals, and the transmitting unit 120 of UE100 transmits a Measurement Report message including the measurement results to node 200, for example, on the PCell. Here, it is assumed that the Measurement Report message includes the measurement results of the THz wave cell. The receiving unit 220 of node 200 receives the Measurement Report message.

[0114] In step S202, the control unit 230 of node 200 generates an RRC Reconfiguration message, and the transmitting unit 210 of node 200 transmits the RRC Reconfiguration message to UE100, for example, on the PCell. The receiving unit 110 of UE100 receives the RRC Reconfiguration message.

[0115] The RRC Reconfiguration message includes, for example, setting information for adding an SCell, setting information for designating the active state as the initial state of the SCell, setting information for setting a BWP (dedicated BWP) for the SCell, and setting information for conditional dormant BWP transition. In the illustrated example, the setting information for adding an SCell, the setting information for designating the active state as the initial state of the SCell, the setting information for setting a BWP (dedicated BWP) for the SCell, and the setting information for conditional dormant BWP transition are transmitted in one RRC Reconfiguration message, but these pieces of information may be transmitted in separate RRC Reconfiguration messages.

[0116] The configuration information for adding an SCell may be the sCellToAddModList which is a list of SCell to be added or modified. The sCellToAddModList is a list having SCell configurations (SCellConfig) as entries. Each SCell configuration (SCellConfig) includes the index of the corresponding SCell (sCellIndex) and the configuration of the corresponding SCell (sCellConfigCommon and sCellConfigDedicated). The configuration information for designating the active state as the initial state of the SCell, the configuration information for setting a BWP (dedicated BWP) for the SCell, and the configuration information for conditional dormant BWP transition may be included in the SCell configuration (SCellConfig).

[0117] The configuration information for conditional dormant BWP transition includes information indicating the radio quality conditions to be satisfied for transitioning the BWP to the dormant state when the active BWP of the corresponding active SCell is a non-dormant BWP. The information indicating the radio quality conditions may include at least one radio quality threshold among an RSRP threshold, an RSRQ threshold, and an SINR threshold. The information indicating the radio quality conditions may include at least one of a threshold for the duration of the state in which a radio problem is detected, a threshold for the number of times retransmission continues in the UE100 (i.e., the number of times the failure of UL data transmission continues), and a threshold for the time during which UL data transmission cannot be performed based on detecting an interference wave.

[0118] In the second embodiment, the initial state of the active BWP of the SCell added to the UE100 is a non-dormant state. The control unit 130 of the UE100 starts radio quality measurement for the SCell based on the configuration information for conditional dormant BWP transition.

[0119] In step S203, the control unit 130 of the UE 100 generates an RRC Reconfiguration Complete message, and the transmission unit 210 of the UE 100 transmits the RRC Reconfiguration Complete message to the node 200, for example, on the PCell. The reception unit 220 of the node 200 receives the RRC Reconfiguration Complete message.

[0120] The initial state of the SCell added to the UE 100 may be the active state (step S204). Alternatively, after the SCell is added to the UE 100, the SCell may be activated by a MAC CE (step S204).

[0121] In step S205, the reception unit 110 of the UE 100 receives the reference signal of the SCell, and the control unit 130 of the UE 100 measures the radio quality based on the reference signal. The reference signal of the SCell may be the DMRS included in the SSB transmitted by the SCell, or may be the TRS. The measurement of the radio quality may include at least one of the measurement of the duration of the state in which a radio problem is detected, the measurement of the number of times the retransmission continues, and the measurement of the time when UL data transmission cannot be executed.

[0122] In step S206, the control unit 130 of the UE 100 determines whether the radio quality condition set in step S202 is satisfied. For example, the control unit 130 of the UE 100 compares the measurement result (for example, RSRP, RSRQ, and / or SINR) in step S205 with the radio quality threshold set in step S202, and determines that the radio quality condition is satisfied when the measurement result is lower than the radio quality threshold. When it is determined that the radio quality condition is not satisfied (step S206: NO), the process returns to step S205.

[0123] On one hand, when it is determined that the radio quality condition is satisfied (step S206: YES), in step S207, the control unit 130 of the UE 100 causes the SCell to transition to the dormant state (i.e., switches from the non-dormant state to the dormant state).

[0124] In step S208, the control unit 130 of the UE 100 triggers the transmission of the SCell BWP dormant transition notification, and the transmission unit 120 of the UE 100 transmits the SCell BWP dormant transition notification to the node 200 on the PCell. The receiving unit 220 of the node 200 receives the SCell BWP dormant transition notification.

[0125] The SCell BWP dormant transition notification may include information on the timing at which the SCell BWP dormant transition (i.e., step S207) was performed. The timing information may be the radio frame number at which the SCell BWP dormant transition was executed, or may be expressed by any one or combination of the system frame number, sub-frame number, slot number, and symbol number. The timing information may be the time information at which the SCell BWP dormant transition was executed. The timing information may also be the elapsed time from when the SCell BWP dormant transition was executed until the SCell BWP dormant transition notification is transmitted, and may be expressed in seconds (e.g., milliseconds) or in terms of the number of radio frames (e.g., the number of slots). With such timing information, the node 200 can know when DL reception in the SCell stopped, and can efficiently identify the data packets to be retransmitted when retransmitting the data transmitted during that period on the PCell.

[0126] The SCell BWP dormant transition notification may be a newly introduced MAC CE. The SCell BWP dormant transition notification includes the index value (which may be a cell ID) of the SCell that has transitioned to the dormant BWP and / or the BWP ID of the said BWP. However, the SCell BWP dormant transition notification may be a notification included in the UCI transmitted on the PUCCH, or may be a PDCP Control PDU, or may be a notification included in an RRC message.

[0127] Prior to the transmission of the SCell BWP dormant transition notification, the following processes may be performed in the PHY layer and the MAC layer. Specifically, the UE 100 transmits an SR to the node 200, the node 200 transmits a UL grant for the BSR to the UE 100, the UE 100 transmits a BSR to the node 200, and the node 200 transmits a UL grant for PUSCH transmission to the UE 100. Then, the UE 100 transmits the SCell BWP dormant transition notification based on the UL grant for PUSCH transmission.

[0128] Although an example of the UE 100 transmitting the SCell BWP dormant transition notification to the node 200 on the PCell has been described, the SCell BWP dormant transition notification may also be transmitted to the node 200 on the SCell.

[0129] In step S209, the transmission unit 210 of the node 200 transmits a HARQ ACK indicating successful reception of the SCell BWP dormant transition notification to the UE 100 on the PDCCH of the PCell. The reception unit 110 of the UE 100 receives the HARQ ACK. Note that if the SCell BWP dormant transition notification is a UCI, step S209 may not be performed.

[0130] In response to receiving the SCell BWP dormant transition notification in step S208, node 200 recognizes that the active BWP of the SCell of UE100 has become unavailable. In step S210, node 200 stops DL transmission on the active BWP of the SCell.

[0131] (3) Third Embodiment Referring to FIGS. 13 and 14, the third embodiment will be mainly described with differences from the above-described embodiments. The third embodiment is an embodiment premised on the first embodiment described above. However, the third embodiment may also be an embodiment premised on the second embodiment described above.

[0132] In the above-described embodiments, UE100 detects that the radio quality of the SCell satisfies a predetermined quality and performs SCell deactivation or dormant BWP transition. Here, in order to quickly detect that the radio quality of the SCell satisfies a predetermined quality, it is desirable that UE100 can always measure the radio quality of the SCell. In the above-described embodiments, an example in which UE100 measures the radio quality (RSRP, etc.) using the SSB or TRS (CSI-RS) as a reference signal has been described, but these reference signals are transmitted discretely in time. Therefore, at the timing when the SSB or CSI-RS is not transmitted, UE100 cannot perform radio communication measurement, and a delay may occur when detecting that the radio quality of the SCell satisfies a predetermined quality.

[0133] Therefore, in the third embodiment, the transmission unit 210 of node 200 continuously transmits in the time direction on the SCell a reference signal (also referred to as "Fast tracking RS") used for measuring the radio quality. The receiving unit 110 of UE100 receives the Fast tracking RS continuously transmitted in the time direction on the SCell from node 200. The control unit 130 of UE100 measures the radio quality of the SCell based on the Fast tracking RS. Thereby, the above-described delay can be suppressed.

[0134] FIG. 13 is a diagram showing a specific example of Fast tracking RS according to the third embodiment. In the Fast tracking RS according to the third embodiment, Fast tracking RS is arranged in a part of the frequency resources of the bandwidth of a secondary cell (SCell).

[0135] In the example of (1) in FIG. 13, Fast tracking RS is arranged in one or more resource blocks in the center of the bandwidth of the SCell, or in one or more subcarriers in the center of the bandwidth of the SCell. In the example of (2) in FIG. 13, Fast tracking RS is arranged in one or more resource blocks on one end side of the bandwidth of the SCell, or in one or more subcarriers on one end side of the bandwidth of the SCell. In the example of (3) in FIG. 13, Fast tracking RS is arranged in one or more resource blocks on both end sides of the bandwidth of the SCell, or in one or more subcarriers on both end sides of the bandwidth of the SCell.

[0136] FIG. 14 is a diagram showing an example of system operation according to the third embodiment. In FIG. 14, steps that are not essential are indicated by dashed lines. Also, duplicate descriptions of operations similar to those in the first embodiment described above are omitted.

[0137] In step S301, the transmission unit 120 of the UE 100 transmits a Measurement Report message to the node 200, for example, on the PCell. The reception unit 220 of the node 200 receives the Measurement Report message.

[0138] In step S302, the transmission unit 210 of the node 200 transmits an RRC Reconfiguration message to the UE 100, for example, on the PCell. The reception unit 110 of the UE 100 receives the RRC Reconfiguration message.

[0139] In the third embodiment, the RRC Reconfiguration message may include configuration information regarding Fast tracking RS in addition to the information described in the first embodiment above. The configuration information regarding Fast tracking RS includes at least one of information indicating the presence or absence of Fast tracking RS, information indicating the position on the frequency axis of Fast tracking RS (e.g., resource block number, subcarrier number, and / or ARFCN (Absolute Radio-Frequency Channel Number)), and information assisting in demodulation of Fast tracking RS (e.g., root sequence number indicating the signal sequence of the reference signal, etc.).

[0140] Alternatively, Node 200 may broadcast the configuration information regarding Fast tracking RS in the system information block (SIB) of the PCell.

[0141] In step S303, the transmitter 210 of UE100 transmits an RRC Reconfiguration Complete message to Node 200, for example, on the PCell. The receiver 220 of Node 200 receives the RRC Reconfiguration Complete message.

[0142] The initial state of the SCell added to UE100 may be the active state (step S304). Alternatively, after the SCell is added to UE100, the SCell may be activated by MAC CE (step S304).

[0143] In step S305, the transmitter 210 of Node 200 transmits a stationary Fast tracking RS on the time axis in the SCell to be fast-detected. The receiver 110 of UE100 receives the Fast tracking RS on the SCell.

[0144] In step S306, the control unit 130 of the UE 100 measures the radio quality based on the Fast tracking RS of the SCell.

[0145] In step S307, the control unit 130 of the UE 100 determines whether the radio quality condition set in step S302 is satisfied. If it is determined that the radio quality condition is not satisfied (step S307: NO), the process returns to step S306.

[0146] If it is determined that the radio quality condition is satisfied (step S307: YES), in step S308, the control unit 130 of the UE 100 deactivates the SCell.

[0147] In step S309, the transmission unit 120 of the UE 100 transmits an SCell deactivation notification to the node 200 on the PCell. The reception unit 220 of the node 200 receives the SCell deactivation notification.

[0148] In step S310, the transmission unit 210 of the node 200 transmits a HARQ ACK indicating the reception success of the SCell deactivation notification to the UE 100 on the PDCCH of the PCell. The reception unit 110 of the UE 100 receives the HARQ ACK. Note that if the SCell deactivation notification is UCI, step S308 may not be performed.

[0149] In step S311, the node 200 stops DL transmission to the UE 100 via the SCell.

[0150] (4) Other Embodiments The above-described first to third embodiments may be implemented separately and independently, or two or more embodiments may be combined and implemented.

[0151] In the above-described embodiments, an example in which the SCell is a THz wave cell has been mainly described, but the SCell is not limited to the THz wave cell. For example, the SCell may be a mmW cell.

[0152] UE100 may be the MT (Mobile Termination) of an IAB (Integrated Access and Backhaul) node. In this case, the IAB MT may be connected to the first node, and the first node may be connected to the second node. The first node may send a notification indicating a radio link failure of the backhaul link between the first node and the second node to the IAB MT. When receiving the notification, the IAB MT may determine that the radio quality condition is satisfied and perform SCell deactivation (or dormant BWP transition).

[0153] The operation flow in the above-described embodiments does not necessarily have to be executed in time series in the order described in the flowchart. For example, the steps in the operation may be executed in an order different from the order described as the flowchart, or may be executed in parallel. Also, some of the steps in the operation may be deleted, and additional steps may be added to the process.

[0154] A program for causing a computer (UE100, node 200) to execute the operations according to the above-described embodiments may be provided. The program may be recorded on a computer-readable medium. By using the computer-readable medium, it is possible to install the program on the computer. Here, the computer-readable medium on which the program is recorded may be a non-transitory recording medium. The non-transitory recording medium is not particularly limited, and may be, for example, a recording medium such as a CD-ROM or a DVD-ROM.

[0155] As used in this disclosure, the terms "based on" and "depending on / in response to" do not mean "only based on" or "only in response to" unless otherwise specified. The term "based on" means both "only based on" and "at least partially based on". Similarly, the term "depending on" means both "only in response to" and "at least partially in response to". Also, the terms "include", "comprise", and their variants do not mean only including the listed items, but may mean including only the listed items or including additional items in addition to the listed items. Further, the term "or" used in this disclosure is not intended to be an exclusive disjunction. Additionally, any reference to elements using designations such as "first", "second", etc. used in this disclosure does not generally limit the quantity or order of those elements. These designations can be used in this specification as a convenient way to distinguish between two or more elements. Thus, a reference to the first and second elements does not mean that only two elements can be employed there or that the first element must precede the second element in some form. In this disclosure, for example, when articles are added by translation like a, an, and the in English, these articles are assumed to include plural ones unless the context clearly indicates otherwise.

[0156] As described above in detail with reference to the drawings, the specific configuration is not limited to the above, and various design changes and the like can be made without departing from the gist.

[0157] (5) Supplementary Note The features regarding the above-described embodiments are noted.

[0158] (Supplementary Note 1) A user device that performs wireless communication with a node using carrier aggregation in a mobile communication system, A receiving unit that receives, from the node, information indicating radio quality conditions to be satisfied for the user equipment to perform deactivation processing on a secondary cell set in the user equipment; A control unit that measures radio quality and evaluates whether the radio quality conditions are satisfied; and The control unit performs the deactivation processing on the secondary cell in response to the radio quality conditions being satisfied. User equipment.

[0159] (Appendix 2) The deactivation processing includes processing for transitioning the secondary cell in an active state to an inactive state. The user equipment according to Appendix 1.

[0160] (Appendix 3) The deactivation processing includes processing for transitioning a bandwidth portion in a non-dormant state in the secondary cell to a dormant state. The user equipment according to Appendix 1 or 2.

[0161] (Appendix 4) The user equipment further includes a transmitting unit that transmits a notification regarding the deactivation processing to the node in response to the radio quality conditions being satisfied. The user equipment according to any one of Appendices 1 to 3.

[0162] (Appendix 5) The transmitting unit transmits the notification to the node on a primary cell. The user equipment according to Appendix 4.

[0163] (Appendix 6) The control unit stops monitoring a physical downlink control channel (PDCCH) for the secondary cell when the radio quality conditions are satisfied or when an affirmative response to the notification is received from the node. The user equipment according to Appendix 4 or 5.

[0164] (Appendix 7) The receiving unit receives a reference signal continuously transmitted in the time direction on the secondary cell from the node, and the control unit measures the radio quality based on the reference signal. The user equipment according to any one of Appendices 1 to 6.

[0165] (Appendix 8) A node that performs wireless communication with a user equipment using carrier aggregation in a mobile communication system, comprising a control unit that sets a secondary cell for the user equipment, and a transmitting unit that transmits to the user equipment information indicating a radio quality condition to be satisfied for the user equipment to perform deactivation processing on the secondary cell. Node.

[0166] (Appendix 9) The deactivation processing includes processing for transitioning the secondary cell in an active state to an inactive state. The node according to Appendix 8.

[0167] (Appendix 10) The deactivation processing includes processing for transitioning a bandwidth portion in a non-dormant state in the secondary cell to a dormant state. The node according to Appendix 8 or 9.

[0168] (Appendix 11) The node further comprises a receiving unit that receives from the user equipment a notification regarding the deactivation processing in response to the radio quality condition being satisfied in the user equipment. The node according to any one of Appendices 8 to 10.

[0169] (Appendix 12) The receiving unit receives the notification from the user equipment on the primary cell. The node according to Appendix 11.

[0170] (Appendix 13) When receiving the notification or when transmitting an affirmative response to the notification to the user equipment, the control unit stops the downlink transmission process on the secondary cell. The node according to Appendix 11 or 12.

[0171] (Appendix 14) The transmission unit continuously transmits, in the time direction, a reference signal used for measuring the radio quality on the secondary cell. The node according to any one of Appendices 8 to 13.

[0172] (Appendix 15) A communication method used in a user equipment that performs wireless communication with a node using carrier aggregation in a mobile communication system, the method comprising: receiving, from the node, information indicating a radio quality condition to be satisfied for the user equipment to perform a deactivation process on a secondary cell set in the user equipment; measuring radio quality and evaluating whether the radio quality condition is satisfied; performing the deactivation process on the secondary cell in response to the radio quality condition being satisfied. Communication method.

[0173] (Appendix 16) A communication method used in a node that performs wireless communication with a user equipment using carrier aggregation in a mobile communication system, the method comprising: setting a secondary cell for the user equipment; transmitting, to the user equipment, information indicating a radio quality condition to be satisfied for the user equipment to perform a deactivation process on the secondary cell. Communication method.

Explanation of Reference Numerals

[0174] 1: Network 10: RAN 20: CN 100: UE 110: Receiver unit 120: Transmitter unit 130: Control unit 140: Wireless communication unit 200: Node 210: Transmitter unit 220: Receiver unit 230: Control unit 240: NW communication unit 250: Wireless communication unit 300: CN device

Claims

1. A user equipment that performs wireless communication with a node using carrier aggregation in a mobile communication system, a receiving unit that receives, from the node, information indicating a radio quality threshold of a cell that should be satisfied for the user equipment to execute a deactivation process for a secondary cell in an active state set in the user equipment; a control unit that measures radio quality for the secondary cell in the active state and evaluates whether or not the condition of the radio quality threshold is satisfied, and when the condition of the radio quality threshold is satisfied, the control unit immediately executes the deactivation process for the secondary cell in the active state, wherein the deactivation process is a process not involving an activation process of another secondary cell in an inactive state set in the user equipment User equipment.

2. The deactivation process includes a process of transitioning the secondary cell in the active state to an inactive state The user equipment according to claim 1.

3. The deactivation process includes a process of transitioning an active bandwidth portion in a non-dormant state in the secondary cell to a dormant state The user equipment according to claim 1.

4. The user equipment further includes a transmission unit that transmits a notification including an identifier of the secondary cell for which the deactivation process is to be performed to the node in response to the condition of the radio quality threshold being satisfied The user equipment according to any one of claims 1 to 3.

5. The transmission unit transmits the notification to the node on a primary cell The user equipment according to claim 4.

6. When the condition of the radio quality threshold is satisfied or when an affirmative response to the notification is received from the node, the control unit stops monitoring a physical downlink control channel (PDCCH) for the secondary cell The user equipment according to claim 4.

7. The receiving unit receives a reference signal continuously and steadily in the time direction on the secondary cell from the node, and the control unit measures the radio quality based on the reference signal The user equipment according to claim 1.

8. When the user equipment is in an RRC connected state, the receiving unit receives, from the node, information indicating the radio quality threshold, The control unit While maintaining the RRC connected state, evaluate whether the conditions of the radio quality threshold are satisfied. In response to the conditions of the radio quality threshold being satisfied, execute the deactivation process while maintaining the RRC connected state. The user equipment according to claim 1.

9. A node that performs wireless communication with a user equipment using carrier aggregation in a mobile communication system, a control unit that sets a secondary cell for the user equipment, a transmission unit that transmits to the user equipment information indicating a radio quality threshold of a cell that should be satisfied for the user equipment to execute a deactivation process for the active secondary cell, and in the user equipment, when the conditions of the radio quality threshold are satisfied, cause the user equipment to immediately execute the deactivation process for the active secondary cell, the deactivation process is a process that does not involve an activation process of another secondary cell in the inactive state set for the user equipment. Node.

10. The deactivation process includes a process of transitioning the secondary cell in the active state to the inactive state. The node according to claim 9.

11. The deactivation process includes a process of transitioning an active bandwidth portion in the non-dormant state in the secondary cell to the dormant state. The node according to claim 9.

12. Further comprising a reception unit that receives from the user equipment a notification including an identifier of the secondary cell for which the deactivation process is to be performed in response to the conditions of the radio quality threshold being satisfied in the user equipment. The node according to any one of claims 9 to 11.

13. The reception unit receives the notification from the user equipment on the primary cell. The node according to claim 12.

14. When receiving the notification or when transmitting an affirmative response to the notification to the user equipment, the control unit stops the downlink transmission process on the secondary cell. The node according to claim 12.

15. The transmission unit continuously and steadily transmits in the time direction on the secondary cell a reference signal used for measuring radio quality. The node according to claim 9.

16. The control unit sets the secondary cell for the user equipment in the RRC connected state. The transmitting unit transmits, to the user equipment, information indicating the radio quality threshold that should be satisfied for the user equipment to execute the deactivation process while maintaining the RRC connected state. The node according to claim 9.

17. A communication method used in a user equipment that performs wireless communication with a node using carrier aggregation in a mobile communication system, comprising: receiving, from the node, information indicating a radio quality threshold of a cell that should be satisfied for the user equipment to execute a deactivation process for a secondary cell in an active state set in the user equipment; measuring the radio quality of the secondary cell in the active state and evaluating whether the condition of the radio quality threshold is satisfied; immediately executing the deactivation process for the secondary cell in the active state in response to the condition of the radio quality threshold being satisfied, and having: The deactivation process is a process that does not involve an activation process of another secondary cell in an inactive state set in the user equipment. Communication method.

18. In the receiving step, when the user equipment is in the RRC connected state, information indicating the radio quality threshold is received from the node. In the evaluating step, while maintaining the RRC connected state, it is evaluated whether the condition of the radio quality threshold is satisfied. In the step of executing the deactivation process, in response to the condition of the radio quality threshold being satisfied, the deactivation process is executed while maintaining the RRC connected state. The communication method according to claim 17.

19. A communication method used in a node that performs wireless communication with a user equipment using carrier aggregation in a mobile communication system, comprising: setting a secondary cell for the user equipment; transmitting, to the user equipment, information indicating a radio quality threshold of a cell that should be satisfied for the user equipment to execute a deactivation process for the secondary cell in an active state, and having: In the user equipment, when the condition of the radio quality threshold is satisfied, the deactivation process for the secondary cell in the active state is immediately executed. The deactivation process is a process that does not involve the activation process of another secondary cell in the deactivated state set in the user equipment. Communication method.

20. In the setting step, the secondary cell is set for the user equipment in the RRC connected state. In the transmitting step, information indicating the radio quality threshold to be satisfied for the user equipment to execute the deactivation process while maintaining the RRC connected state is transmitted to the user equipment. The communication method according to claim 19.

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